Dentistry requires accurate 3-D representation of the teeth and jaw for diagnostic and treatment purposes. For example, orthodontic treatment involves the application, over time, of force systems to teeth to correct malocclusion. In order to evaluate tooth movement progress, the orthodontist monitors this movement by means of visual inspection, intra-oral measurements, fabrication of casts, photographs, and radiographs; this process is both costly and time consuming. Moreover, repeated acquisition of radiographs may result in untoward effects. Obtaining a cast of the jaw is a complex operation for the dentist, an unpleasant experience for the patient, and also may not provide all the necessary details of the jaw.
Oral and maxillofacial radiology provides the dentist with abundant 3-D information of the jaw. Current and evolving methods include computed tomography (CT), tomosynthesis, tuned-aperture CT (TACT), and localized, or “cone-beam,” computed tomography. While oral and maxillofacial radiology is now widely accepted as a routine technique for dental examinations, the equipment is rather expensive and the resolution is frequently too low for 3-D modeling of dental structures. Furthermore, the radiation dose required to enhance both contrast and spatial resolution can be unacceptably high.
Much effort has been focused recently on computerized diagnosis in dentistry. One solution is an expert system where cephalometric measurements are acquired manually from the analysis of radiographs and plaster models. Another solution provides a computer-vision technique for the acquisition of jaw data from inexpensive dental wafers, which is capable of obtaining imprints of the teeth. Conventional 3-D systems for dental applications commonly rely on obtaining an intermediate solid model of the jaw (cast or teeth imprints) and then capturing the 3-D information from that model. User interaction is needed in such systems to determine the 3-D coordinates of fiducial reference points on a dental cast. Other systems that measure the 3-D coordinates have been developed using either mechanical contact or a traveling light principle. Yet another conventional solution includes a range scanner based on white light to reconstruct the cast. The scanner used the subtractive light principle to create very thin shadow profiles on the cast.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a general need to replace conventional approaches in diagnosis, treatment planning, surgical simulation and prosthetic replacements. More specifically, there is a need in the art for three-dimensional (3-D) dental imagery not using expensive, low-resolution and potentially harmful radiography, intermediate physical casts. There is also a need for fabricating dental casts in a manner that does not require time consuming and non-renewable direct application of material to the dental surfaces. Moreover, there is a need for a data acquisition system that obtains sequences of calibrated video images, with respect to a common reference in 3-D space, of the upper and/or lower jaw using an intraoral cavity camera. There is also a need for methods of accurate 3-D reconstruction of the upper and/or lower jaw from the acquired sequence of intraoral cavity images. There is a further need for a shape-from-shading process that incorporates the parameters of the intraoral cavity camera. There is yet another need for a robust process for the fusion of data acquired from multiple views of the intraoral cavity camera. There is still another need for the implementation of a fast an accurate 3-D registration. There is still yet another need for specific object segmentation and recognition of individual tooth information for further analysis and simulations. There is still yet a further need to enable study and simulation of tooth movement based on finite element and deformable model methods.